(Reuters) – An experimental drug to treat Morquio A Syndrome, a rare genetic disorder that causes skeletal malformation and a variety of related lung, eye, ear and heart problems, should be approved, an advisory panel to the U.S. Food and Drug Administration concluded on Tuesday.

The 21-member panel voted overwhelmingly in favor of approval, saying the benefits of the drug, Vimizim, which is made by BioMarin Pharmaceutical Inc, outweigh its risks. The FDA is not obliged to follow the recommendations of its advisory panels but typically does so.

Morquio A Syndrome is characterized by a deficiency of an enzyme known as N-acetylgalactosamine-6-sulfatase, which causes excessive storage in the body of long chains of sugars known as glycosaminoglycans.

This build-up can lead to short stature and joint abnormalities that limit mobility and endurance. The disease can also cause hearing loss, eye problems and heart disease. Symptoms often appear before the age of five.

Children who took the drug during clinical testing saw an improvement in energy and endurance, allowing them to better socialize, learn and function independently, families who testified before the panel said.

The main goal of the trial was to improve symptoms as measured by a six-minute walk test. A secondary goal was change measured by a three-minute stair climb test.

After 24 weeks of treatment with the drug, Vimizim increased patients’ six-minute walk distance by 22.5 meters compared with a placebo, a benefit the FDA reviewers called “modest.” There was no statistically meaningful improvement in the stair climb test.

Nonetheless, the panel decided that the walk test probably captured only a portion of the benefits conferred by the drugs, though the exact nature of the additional benefits and their magnitude remain unclear.

Vimizim, also known as elosulfase alfa, is expected to generate sales of $ 532 million by 2018 if approved, according to the average estimate of eight analysts polled by Thomson Reuters.

Morquio A Syndrome is one of a group of lysosomal storage disorders known as mucopolysaccharidoses (MPS). Lysosomal storage disorders are typically chronic and progressive, and involve multiple organs of the body.

Vimizim has been given “orphan drug” status by the FDA, which means it will receive seven years of market exclusivity if approved. An orphan drug treats diseases that affect fewer than 200,000 patients.

The main safety concerns of the drug relate to anaphylaxis and allergic reactions. The panel said such side effects are consistent with other enzyme replacement therapies and that the benefits outweigh the risks.